1. Field of the Invention
This invention relates to a yarn treating composition useful in friction draw-false twist texturing of synthetic filamentary yarns such as polyamide or polyester yarns. More particularly, it relates to a yarn treating composition wherein scum deposition is scarcely any observed on a high-temperature heater in friction draw-false twist texturing at a high speed.
2. Description of the Prior Art
Synthetic filamentary yarns such as polyamide or polyester yarns have been recently drawn and false twisted simultaneously. The adoption of the friction false twisting method (hereinafter referred to as the "friction method") has remarkably increased the draw-false twisting speed compared with the conventional spindle method. Even with the friction method, the speed has been further increased due to the development of various mechanical devices, and recently directed rapidly from 400 m/min or higher up to 1000 m/min. However, yarns are frequently exposed to severer conditions because of the increased heat-treating temperature due to the increases in contact pressure at areas of contact between the yarns and various substrates, for example, guides, rollers, and heaters, and in texturing speed with increasing texturing speed. For example, the friction between the yarns and various substrates increases greatly with increasing texturing speed, and as a result the yarns are damaged to increase the occurrence of snow powder comprising oligomers and the like, fluffs, and broken yarn, thus deteriorating the processability. Furthermore, the increased speed of rotating bodies resulting from the increase in the yarn speed extremely deteriorates the operating efficiency, such as threading property. The false twisting speed, which increases more remarkably corresponding to the increasing texturing speed, applies very great centrifugal force to yarns, and the conventional well-known treating agent is squeezed out from the surfaces of yarns and shaken off, and the amount to be splashed on the heater is increased. As a result, the heater is considerably stained, and in the extreme, the disadvantage of so-called "tar flowing" wherein the agent flows through the heater groove occurs. Gels or non-volatile sludge residues on the heater resulting from components subject to thermal decomposition in the agent markedly deteriorate the frictional properties of the yarns to cause fluffing in texturing, or abnormal crimping, eventually resulting in yarn breakage. Thus, in order to increase the productivity, the heater must be cleaned frequently. However, the frequent cleaning of the heater adversely deteriorates the productivity, thus incurring the high cost. For solving the problems described above, heat-resistant finish oils have been studied recently, and finish oils consisting mainly of various polyether compounds have been proposed extensively. In more detail, lubricants consisting of a copolymer of propylene and ethylene oxides have long been known, and their general properties have been clarified. On closer investigations, the change in copolymerization ratio generally changes considerably the properties of the copolymer even of propylene and ethylene oxides. For example, the behavior of the copolymer depends largely on the number of end groups, copolymerization ratio between propylene and ethylene oxides, the molecular weight, and additives. In general, the copolymer of propylene and ethylene oxides is soluble in water, and the high copolymerization ratio of ethylene oxide increases the water-solubility, while the tendency to increase the residue after heating has been verified experimentally. In contrast, a copolymer of high copolymerization ratio of propylene oxide exhibits such characteristics that the cloud point is lowered considerably at a specific ratio or higher and the aqueous solution becomes very unstable. Finally, a stable aqueous solution cannot be obtained without an emusifier. Consequently, the copolymer of propylene and ethylene oxides involves extensive problems to be defined corresponding to individual technical subjects to be solved.
To illustrate the problems described above more fully, the copolymer of ethylene and propylene oxides is generally stable to oxidation or thermal decomposition at 200.degree. C. or below, however, decomposed by a long-term exposure to a temperature of 200.degree. C. or above. After the decomposition, the copolymer forms residues such as sludges or varnishes, and further deposits. It has been known that the copolymer forms less sludges than mineral oil and synthetic ester compounds. Polyethylene glycol consisting solely of ethylene oxide among polyether lubricants, however, forms more sludges after heating than the copolymer of propylene and ethylene oxides, and cannot be used as a base for treating agents in high-speed texturing. However, it has been found that the copolymer of higher copolymerization ratio of propylene oxide, namely, of molar ratio between propylene and ethylene oxides (hereinafter referred to as PO/EO) of 35:65 or higher, i.e. the propylene oxide content of 35 mole % or higher, may be sufficiently used to reduce the sludge residues. Nevertheless, the characteristics described above are not directly suitable to the agent for treating high-speed false twisting yarns. The operating conditions and processability are still unstable even with said polyether lubricant alone. Therefore, an antistatic agent is usually mixed in use. However, anionic, nonionic, other cationic, or ampholytic surfactants well known as antistatic agents in amounts described in examples of the specifications of Japanese Patent Publication No. 52-47079 (1977) and Japanese Patent Laid-open No. 50-155796 (1975) for the well-known finish oils deposit scums on heaters in high-speed texturing for several hours to several days. The tar formation deteriorates the frictional properties of yarns markedly. Consequently, scum deposits on heaters can be reduced simply by decreasing the amount of the antistatic agent. With 4.0% or less of the agent, the scum deposits on heaters are reduced more than with about 10 to 15%; however, the initial threading property and processability become unstable. For example, a composition comprising 2 to 50% based on the polyether lubricant of anionic surfactants, such as one or two or more compounds selected from sodium or potassium salt of lauric, palmitic or oleic acid of the general formula ##STR1## and/or sodium or potassium salt of octylphosphonic, laurylphosphonic, or oleylphosphonic acid, sodium or potassium salt of polyoxyethylene (3 moles) laurylphosphonic acid of the general formula ##STR2## and/or sodium or potassium salt of polyoxyethylene (3 moles) cetyl sulfate of the general formula EQU RO(CH.sub.2 CH.sub.2 O).sub.n SO.sub.3 M,
is proposed in the specification of Japanese Patent Publication No. 52-47079 (1977). In this case, the large amount of the surfactant increases scum deposits on heaters naturally, and the processing stability is not good in the range of 2% by weight to 4.0% by weight inclusive possibly due to the insufficient antistatic properties at a high speed. Accordingly, in general 6.0% by weight or more of an anionic surfactant is often used to effect the stable texturing.
The specification of Japanese Patent Laid-open No. 50-155796 (1975) discloses a finish oil consisting of 35 to 95% by weight of a polyether lubricant, 4 to 50% by weight of an ordinary nonionic surfactant consisting of an ether or ester of a polyoxyethylene having long-chain alkyl groups, 1 to 30% by weight of a metal salt of a polyethylenepolypropylene glycol higher alcohol ether phosphate, and 1 to 30% by weight of a metal salt of an alkylsulfonate.
According to the proposal described above, an anionic and a nonionic surfactants are always present together, and scum deposits on heaters cannot be easily reduced even by the use of 1 to 4% by weight of an anion salt in high-speed texturing.